US 6939258 B2
A unitary blade unit for an archery broadhead includes a tip structure and at least three blades inseparably connected into a single blade unit. The blade unit requires a separate ferrule in order for the blade unit to be secured to an arrow. Thus, the blade unit can be replaced while retaining a previously used ferrule, or vice versa. In a preferred embodiment, the blade unit is formed by metal injection molding.
1. A unitary blade unit for a modular broadhead, comprising;
a tip structure; and
three or more blades permanently connected into a single blade-unit, wherein at least two of the blades contain a portion that extends toward the tip structure;
wherein the blade unit requires a separate ferrule in order for the blade unit to be secured to an arrow.
2. The blade unit of
3. The blade unit of
4. The blade unit of
5. The unitary blade unit of
6. The blade unit of
7. The blade unit of
8. The blade unit of
9. The blade unit of
10. The blade unit of
11. The unitary blade unit of
12. The unitary blade unit of
13. The unitary blade unit of
This application claims priority to, and incorporates by reference, the U.S. Provisional Patent Application No. 60/354,214, filed Feb. 4, 2002, and the U.S. Provisional Patent Application No. 60/365,249, filed Mar. 18, 2002. This application also claims priority to, is a continuation-in-part of, and incorporates by reference the U.S. Utility patent application Ser. No. 09/922,550, filed Aug. 4, 2001, which in turn claims priority to the now-expired U.S. Provisional Patent Application No. 60/265,114, filed Jan. 31, 2001, and the now-expired U.S. Provisional Patent Application No. 60/293,307, filed May 24, 2001. This application also claims priority to, is a continuation-in-part of, and incorporates by reference the U.S. Utility patent application Ser. No. 10/094,125, filed Mar. 8, 2002, which in turn claims priority to the now-expired U.S. Provisional Patent Application No. 60/273,819, filed Mar. 8, 2001, and the now-expired U.S. Provisional Patent Application No. 60/286,030, filed Apr. 24, 2001.
The present invention generally relates to archery equipment. More particularly, the present invention relates to a unitary broadhead blade unit for hunting arrows, along with a method for manufacturing a unitary blade unit for a modular broadhead.
Traditionally, archery broadheads are made from multiple pieces that are fitted together. The pieces may include individual blades, a tip, and/or other connecting parts. Traditional broadheads also include a means for connecting the broadhead to an arrow, such as a receptacle designed to fit over the shaft of an arrow, with threads or glue to secure the broadhead to an arrow. However, such broadheads can be expensive to manufacture, and they can become loose, and may even separate, through use or transport.
One attempt to overcome this problem is described in U.S. Pat. No. 6,290,903, to Grace, Jr. As described in
Accordingly, it is desirable to provide an improved unitary blade unit for a modular broadhead.
In accordance with a preferred embodiment of the invention, a unitary blade unit for a modular broadhead includes a tip structure and three or more blades inseparably connected into a single blade-unit. Each blade contains a portion that extends toward the tip structure. Further, the blade unit requires a separate ferrule in order for the blade unit to be secured to an arrow.
Optionally, the blade unit also includes a first adapter to separably connect the blade unit to the ferrule. The adapter may include a cap that is sized and positioned to receive a first portion of the ferrule, and/or a collar that is sized and positioned to receive a second portion of the ferrule. Either or both portions of such an adapter may be integral with or separate from the blade unit. Optionally, the blade unit may also include a second separate adapter for further securing the blade unit to the ferrule.
As further options, the blade unit is preferably formed as a single unit by metal injection molding. In this embodiment, each of the blades preferably has a thickness near a base area that is greater than a thickness at an outer edge. Alternatively, the blade unit may be formed by welding the three or more blades into a single, inseparable unit. In either case, the blade unit is preferably made of metal. Preferably, the tip structure of the blade unit is integrally comprised of front points of the three or more blades. However, in an alternate embodiment the tip structure may extend from front areas of the three or more blades.
A preferred method of manufacturing a blade unit for a modular broadhead may include the steps of providing a mold having one or more cavities that define a multiple-bladed blade unit having two or more blades, inserting a mixture of metal and binder into the mold, compacting the mixture in the mold to form an intermediate blade unit, processing the intermediate blade unit to remove at least a portion of the binder, sintering the intermediate blade unit to form a sintered blade unit, and sharpening the blades to form a cutting edge on each blade to yield a final blade unit. The final blade unit requires a separate ferrule in order to attach to an arrow. Preferably, in this method the mixture is in powdered form, and the sintering step comprises sintering at an elevated temperature and pressure.
Alternately and optionally, the method of manufacturing a blade unit for a modular broadhead may include using metal injection molding to form a blade unit from a mixture that includes metal and a binder, wherein the blade unit has at least two blades and requires a separate ferrule in order to attach to an arrow. In this embodiment, the method may also include the step of manufacturing a separate adapter for securing the blade unit to the ferrule. It may also include forming the blade unit to include a first integral adapter for securing the blade unit to the ferrule, and optionally manufacturing a second separate adapter for further securing the blade unit to the ferrule.
In the embodiment illustrated in
In the preferred embodiment shown in
The base collar 20 such as that illustrated in
In the preferred embodiment of
The frontal point 18 of the blade unit is the first part that will contact a target. Since it is just a point, and since it will receive a tremendous force upon impact, it is preferred that the blade unit be constructed in such a way that it has additional strength. This can be accomplished by tapered grinding, moving over a sharpening stone, or other sharpening of the razor edges 12. With such a procedure, each razor edge 12 may be sharpened at an angle that is greater than the angle that the razor edge 12 is adjacent to the base 14 of the blade 16. Near the frontal point 18, the angle is preferably less sharp, this providing a wider cutting edge near the frontal point 18 than near the base 14.
The unitary blade unit is preferably made of any metal. More preferably, the unitary blade unit is made using carbon steel, stainless steel, spring steel, tool steel, or titanium, or a composition including any of the above.
In a preferred method of manufacturing the unit using metal injection molding, the steps shown in
Alternatively, the blade unit may be made by assembling the blades into a unitary structure. Preferably, with this method the blades will be fastened together using any commonly known welding procedure such as laser welding, electron beam welding, TIG welding, plasma welding, resistance welding, electron beam welding, fusion welding, pressure welding, friction welding, ultrasonic welding, or other welding methods. Preferably, when manufacturing the unit by welding, the weld of each seam is begun at or near the frontal point and proceeds toward the base. Alternatively, fastening methods other than welding may be used. Exemplary laser welding equipment and procedures are illustrated in FIG. 10. Referring to
The unitary blade unit provides several advantages over the prior art. For example, by providing a separate blade unit and ferrule, a user can replace only one part (i.e., either the blade or the ferrule) without replacing the other, thus reducing replacement costs. In addition, the separation of blade and ferrule allows the manufacturer to provide a weight-adaptable broadhead by manufacturing a standard blade unit and varying ferrules having different weights. In addition, the blade unit and the ferrule may be made of different materials. Thus, the weight of the overall broadhead (i.e., the combination of the blade and ferrule) optionally may be varied by changing the ferrule without replacing the blades, or vice versa. Further, although the blade-unit can be sharpened by grinding, polishing, sanding, or any standard sharpening method, the user may decide to simply dispose of the unitary blade unit and attach a new blade unit to an existing ferrule, resulting in ease of use for the user and the potential for increased sales for the manufacturer.
When made by metal injection molding, the blade unit designer receives a tremendous amount of freedom in the shaping and designing of the unit. Exact radii, tapering, and other intricacies can be achieved with minimal cost difference. Metal injection molding also allows metal parts to have a complex geometry with great strength.
The many features and advantages of the invention are apparent from the detailed specification. Thus, the invention is intended to include all such features and advantages of the invention which fall within the true spirits and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is desired to limit the invention to the exact construction and operation illustrated and described in the specification, claims, and drawings herein. Accordingly, all appropriate modifications and equivalents may be included within the scope of the invention.